Silicone foam material for battery fire protection

Abstract

The present disclosure relates to a silicone-based fire protection material having a foam structure in which a hollow filler having a d50 of 10 [mu] m to 200 [mu] m is incorporated in a silicone-based polymer foam comprising bubbles wherein the silicone-based fire protection material has a density of 0.1 g / cc to 0.8 g / cc and a Shore A hardness of 1 to 40, and the silicone-based polymer foam has a bubble size d50 of 10 [mu] m to 1000 [mu] m.

Description

Technical Field

[0001] The present disclosure relates to a silicone-based fireproof material, a production method thereof, and a battery pack structure having the material; to the use of the silicone-based fireproof material in a battery pack structure; and to a method for producing a battery pack structure using the silicone-based fireproof material. Background Art

[0002] Driven by advances in lithium-ion battery technology, the automotive industry has been significantly transformed by electric vehicles (EVs) over the past decade. However, thermal runaway in EV batteries can lead to serious fire risks and hazards, becoming a major safety concern. Thermal runaway temperatures in high-energy-density EV batteries can reach temperatures as high as 600°C or above. Few polymer composites can withstand such high temperatures. Thermal insulation materials are currently being used to minimize the propagation of thermal runaway in EV batteries. They require excellent thermal insulation, high flame retardancy, low weight, and good electrical insulation properties.

[0003] There are two known silicone solutions for mitigating battery thermal runaway. One is silicone foam, which is typically chemically foamed but can also be physically foamed, while the other is silicone rubber composite foam incorporating hollow glass beads. Both are effective to a certain extent, but have limitations.

[0004] Silicone foam pads (whether chemically or physically foamed) are too soft for thermal runaway protection of prismatic and pouch cell battery modules. Due to the expansion of the battery during the thermal runaway process, the silicone foam can be over-compressed, resulting in poor insulation performance. On the other hand, silicone rubber composite foam is essentially incompressible. This is acceptable in many cylindrical cell arrays, but is detrimental to prismatic and pouch cells because they undergo very significant expansion and contraction when they undergo charge and discharge cycles. In addition, the density of the rubber can still be too high and the flame retardancy is often lower than required.

[0005] U.S. Patent No. 10,501,597 B2 discloses a silicone rubber composite foam comprising a silicone rubber binder and hollow glass beads, and the silicone rubber composite foam partially or completely fills the open space of the battery module housing and / or partially or completely covers the battery cells and / or partially or completely covers the module housing, and optionally covers the lid of the battery module housing, wherein the silicone rubber composite foam is obtained by curing an addition-curing organopolysiloxane composition X, and wherein the addition-curing organopolysiloxane composition comprises: a) at least one organopolysiloxane A having at least two alkenyl groups bonded to silicon per molecule, each of the alkenyl groups containing 2 to 14 carbon atoms, b) at least one silicon compound B having at least two hydrogen atoms bonded to silicon per molecule, c) hollow glass beads D, and d) a hydrosilylation catalyst C. However, the above-mentioned silicone rubber composite foam material has its own problems as follows:

[0006] a. To achieve low density, a high content of hollow glass beads is required; at the same time, a high content of hollow glass beads will result in high viscosity, making it difficult to process; therefore the density of the composite foam cannot be very low, limiting its thermal insulation during thermal runaway events; and

[0007] b. Lack of cushioning; due to the fact that hollow glass beads cannot withstand significant deformation, their compressive strain is low; minimum compressive strain is required to absorb the original thickness variation of the unit during assembly,

[0008] and allows for thickness variations during charge-discharge cycling of the cell.

[0009] Related technical literature

[0010] 1.US10501597B2 Summary of the Invention

[0011] Problems to be solved by the present invention

[0012] The problem to be solved by the present invention is how to improve the thermal insulation performance during thermal runaway and provide good cushioning performance while maintaining good processability. The concept of the present invention is a silicone-based fireproofing material, preferably in the form of a sheet (pad) with a foam structure, in which hollow fillers are incorporated into a silicone-based polymer foam containing air bubbles, which is used in battery packs. With air bubbles and hollow glass beads in a silicone rubber matrix, the cured and foamed composite material can provide a better balance between thermal insulation performance, cushioning performance and processability for EV battery pack applications.

[0013] Methods used to solve problems

[0014] As a result of careful research, the present inventors have accomplished the present invention by finding that the above-mentioned problems can be solved by a silicone-based fireproof material having a foam structure in which a d 50 The hollow filler is incorporated into a silicone-based polymer foam containing air bubbles, wherein the silicone-based fireproofing material has a density of 0.1 g / cc to 0.8 g / cc and a Shore A hardness of 1-40, and the silicone-based polymer foam has a bubble size d of 10 microns to 1000 microns. 50 .

[0015] In the above-mentioned silicone-based fireproof material, the volume fraction of the hollow filler is 1%-60% based on the total volume of the silicone-based fireproof material. In some embodiments of the present disclosure, the volume fraction of the bubbles is 5%-90% based on the total volume of the silicone-based fireproof material. In some embodiments of the present disclosure, the hollow filler is selected from hollow glass beads, aerogel particles, perlite beads, hollow ceramic beads, floating beads and polymer hollow beads. In some embodiments of the present disclosure, the silicone-based polymer foam is obtained by curing a curable silicone-based composition, which comprises: a) at least one organopolysiloxane having at least two alkenyl groups bonded to silicon per molecule, b) at least one organosilicon crosslinker having at least two and optionally at least three hydrogen atoms bonded to silicon per molecule, c) hollow filler, d) hydrosilylation catalyst, and e) gas foaming agent. In some embodiments of the present disclosure, the curable silicone-based composition further comprises: f) at least one additive selected from an inhibitor that slows down the curing rate, a reactive diluent that reacts by a hydrosilylation reaction, a pigment, a dye, a clay, a surfactant, hydrogenated castor oil, wollastonite, aluminum trihydrate, magnesium hydroxide, halloysite, magnesia magnesite, expandable graphite, zinc borate, mica, and fumed silica. In some embodiments of the present disclosure, the curable silicone-based composition further comprises: g) at least one selected from the group consisting of: a flame retardant additive, a curing catalyst, a rheology modifier, a wetting additive, a surface treatment agent, a colorant, a filler other than a hollow filler, an antioxidant additive, a biocide, an ultraviolet (UV) stabilizer additive, and an adhesion promoter additive. In some embodiments of the present disclosure, the silicone-based fireproof material is applied to a battery pack. In some embodiments of the present disclosure, the silicone-based fireproof material exhibits a compressive strain of ≥10% at 200 kPa.

[0016] In addition, the present disclosure provides a battery pack structure, wherein the silicone-based fireproof material is completely or partially arranged in the space between at least two adjacent individual battery cells. In some embodiments of the present disclosure, the battery cell is prismatic or pouch-shaped.

[0017] In the above battery pack structure, the silicone-based fireproofing material is silicone-based and is cured before being arranged in a space between at least two adjacent individual battery cells.

[0018] In some embodiments of the present disclosure, the silicone-based fire-resistant material is a silicone-based product cured by a curing reaction of a curable silicone-based composition in a space between at least two adjacent individual battery cells.

[0019] In addition, the present disclosure provides a curable silicone-based composition, which is formed into the silicone-based fire-proof material through a curing reaction, and the curable silicone-based composition comprises:

[0020] a) at least one organopolysiloxane having at least two alkenyl groups bonded to silicon per molecule,

[0021] b) at least one organosilicon crosslinker having at least two and optionally at least three hydrogen atoms bonded to silicon per molecule,

[0022] c) hollow fillers,

[0023] d) a hydrosilylation catalyst, and

[0024] e) Gas blowing agent.

[0025] In some embodiments of the present disclosure, each alkenyl group contains 2 to 14 carbon atoms. Optionally, the alkenyl group is selected from the group consisting of vinyl, allyl, hexenyl, decenyl and tetradecenyl. Preferably, the alkenyl group is a vinyl group.

[0026] Furthermore, the present disclosure provides a method for producing a silicone-based fireproof material, the method comprising the steps of:

[0027] Step (I): providing a part A comprising a) at least one organopolysiloxane having at least two alkenyl groups bonded to silicon per molecule and e) a gaseous blowing agent;

[0028] Step (II): providing a part B comprising b) at least one organosilicon crosslinker having at least two hydrogen atoms bonded to silicon per molecule and optionally e) a gaseous blowing agent as a physical blowing agent;

[0029] Step (III): a step of mixing Part A with Part B to form a curable silicone-based composition;

[0030] Step (IV): a step of applying the curable silicone-based composition as a wet slurry layer onto a substrate optionally having a release layer, and

[0031] Step (V): a step of forming a silicone-based fireproof material by curing and foaming the applied curable silicone-based composition.

[0032] In some embodiments of the present disclosure, in step (IV), the thickness of the wet slurry layer of the curable silicone-based composition ranges from 0.2 mm to 10.0 mm. The method for producing the silicone-based fireproofing material further includes a step of controlling the viscosity and / or fluidity of the curable silicone-based composition by adding a rheology modifier before or simultaneously with step (IV).

[0033] Furthermore, the present disclosure provides a method for producing a battery pack structure, the method comprising the following steps:

[0034] Step (BI): a step of completely or partially filling the space between at least two adjacent individual battery cells with a curable silicone-based composition as a wet slurry, and

[0035] Step (B-II): a step of forming a silicone-based fire-proofing material in a space between at least two adjacent individual battery cells by curing and foaming the applied curable silicone-based composition.

[0036] Effects of the present invention

[0037] The present invention makes it possible to produce silicone-based fireproofing materials, preferably sheets, which exhibit a low density of ≤0.8 g / cc and a compressive strain of ≥10% at 200 kPa. According to the thermal insulation test described in the present disclosure, the back surface temperature of the silicone-based fireproofing material is lower than that of the reference sample. Since the loading amount of hollow filler is relatively low in order to achieve the same or comparable density, the silicone-based fireproofing materials of the present invention exhibit better processability compared to those in the prior art, for example, in the prior art where all the voids are created by the hollow filler and the viscosity would be too high to be processed. In addition, the silicone-based fireproofing materials exhibit a temperature of >10 15 High volume resistance of ohm*m.

[0038] It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as claimed. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 is a schematic diagram of an apparatus for testing the thermal insulation performance of the silicone-based fireproofing material according to the present disclosure.

[0040] Figure 2 is the background temperature curve of Example IE-1 according to the present invention.

[0041] Figure 3 Shown are air bubbles and hollow fillers in a silicone-based polymer foam according to the present invention. DETAILED DESCRIPTION

[0042] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. As disclosed herein, "and / or" means "and, or as an alternative to" or "in addition or alternatively". Unless otherwise indicated, all ranges are inclusive.

[0043] As used herein, the term "sheet" or "mat" means a flat product in the form of a mat or sheet having a certain thickness. Generally, "sheet" or "mat" includes mat forms, sheet forms, and other flat form products having various thicknesses.

[0044] As used herein, the term "hollow filler" is understood to mean a particle having a dense or low-porosity shell and free space within the shell. The hollow filler according to the present invention has a shell whose thickness can be controlled.

[0045] As used herein, the term "thickness" refers to the average of at least three measurements of a dry sheet (e.g., a sheet having a thickness of 0.2 mm to 10.0 mm) measured using an Ames Gage, Model 13C-B2600 (Ames Corporation Waltham Mass).

[0046] As used herein, the terms "aerogel" and "aerogel particles" describe a class of structures having low density, an open-porous structure, a large surface area, and nanoscale pore size. Aerogel particles are provided in at least powders, granules, beads, and other suitable forms, and include inorganic, organic, and hybrid organic-inorganic compositions, or some combination of the foregoing forms and / or compositions.

[0047] As used herein, the term "aerogel" refers to a gel obtained in a known manner via the sol-gel process, which has been dried. This term encompasses both suitable aerogels obtained by supercritical drying of the formed gel and gels generally referred to as "xerogels" obtained by evaporative drying at atmospheric pressure. When considering large-scale production of the materials of the present invention, xerogels are highly advantageous due to their low cost, while aerogels exhibit more favorable technical properties but have higher production costs.

[0048] As used herein, the term "polymer" or "polymerization" in the alternative refers to a polymer prepared from one or more different monomers, such as a copolymer, terpolymer, tetrapolymer, pentapolymer, etc., and can be any of a random polymer, a block polymer, a graft polymer, a sequential polymer, or a gradient polymer.

[0049] As used herein, the term "d 50 ” refers to the median particle size / pore diameter, which can be measured by sieving, for example, the expression “a d of 200 μm” 50 ” means that 50% of the particles / pores of the hollow fillers / bubbles have a particle size / pore diameter of 200 μm or more, and 50% of the particles / pores of the hollow fillers / bubbles have a particle size / pore diameter of less than 200 μm.

[0050] In order to effectively alleviate battery thermal runaway, the present invention provides a chemically foamed or physically foamed silicone foam having a hollow filler, for example, selected from hollow glass beads, aerogel particles, perlite beads, floating beads and polymer hollow beads.

[0051] According to the present invention, the silicone-based fireproof material has a foam structure in which a hollow filler is incorporated into a silicone-based polymer foam containing air bubbles. 50 The density of the silicone-based fire retardant is 0.1 g / cc to 0.8 g / cc, 0.1 g / cc to 0.6 g / cc, 0.1 g / cc to 0.4 g / cc, 0.1 g / cc to 0.2 g / cc, 0.2 g / cc to 0.8 g / cc, 0.2 g / cc to 0.6 g / cc, 0.2 g / cc to 0.4 g / cc, 0.4 g / cc to 0.8 g / cc, 0.4 g / cc to 0.6 g / cc, or 0.6 g / cc to 0.8 g / cc. The Shore A hardness of the silicone-based fireproofing material is 1-40, 1-35, 1-30, 1-25, 1-20, 1-10, 1-5, 5-40, 5-35, 5-30, 5-25, 5-20, 5-10, 10-40, 10-35, 10-30, 10-25, 10-20, 20-40, 20-35, 20-30, 20-25, 30-40, 30-35, 25-35 or 35-40. The cell size d of the silicone-based polymer foam is d 5010 microns - 1000 microns, 10 microns - 800 microns, 10 microns - 600 microns, 10 microns - 400 microns, 10 microns - 200 microns, 10 microns - 100 microns, 10 microns - 50 microns, 50 microns - 1000 microns, 50 microns - 800 microns, 50 microns - 600 microns, 50 microns - 400 microns, 50 microns - 200 microns, 50 microns - 100 microns, 100 microns - 1000 microns, 100 microns - 800 microns, 100 microns-600 microns, 100 microns-400 microns, 100 microns-200 microns, 200 microns-1000 microns, 200 microns-800 microns, 200 microns-600 microns, 200 microns-400 microns, 400 microns-1000 microns, 400 microns-800 microns, 400 microns-600 microns, 600 microns-1000 microns, 600 microns-800 microns or 80 microns-1000 microns.

[0052] In the present invention, the hollow filler is at least one selected from hollow glass beads, aerogel particles, perlite beads, hollow ceramic beads, floating beads and polymer hollow beads. In some embodiments, the hollow glass beads are hollow borosilicate glass microspheres.

[0053] In some embodiments, the volume fraction of the hollow filler is 1%-60%, 1%-50%, 1%-40%, 1%-30%, 1%-20%, 1%-10%, 1%-5%, 5%-60%, 5%-50%, 5%-40%, 5%-30%, 5%-20%, 5%-10%, 10%-60%, 10%-50%, 10%-40%, 10%-30%, 10%-20%, 20%-60%, 20%-50%, 20%-40%, 20%-30%, 30%-60%, 30%-50%, 30%-40%, 40%-60%, 40%-50%, or 50%-60%, based on the total volume of the silicone-based fire-resistant material. Alternatively, the loading of the hollow filler in the dry silicone-based fire retardant is 1% to 20% by volume, 1% to 15% by volume, 1% to 10% by volume, 1% to 5% by volume, 5% to 20% by volume, 5% to 15% by volume, 5% to 10% by volume, 10% to 20% by volume, 10% to 15% by volume, or 15% to 20% by volume.

[0054] In some embodiments, the volume fraction of bubbles is 5%-90%, 5%-50%, 5%-40%, 5%-30%, 5%-20%, 5%-10%, 10%-60%, 10%-50%, 10%-40%, 10%-30%, 10%-20%, 20%-60%, 20%-50%, 20%-40%, 20%-30%, 30%-60%, 30%-50%, 30%-40%, 40%-60%, 40%-50%, or 50%-90%, based on the total volume of the silicone-based fire-resistant material.

[0055] In the present invention, aerogel particles can be provided in any suitable form, such as granules, powders and beads. The chemical composition of the aerogel particles includes inorganic, organic, hybrid organic-inorganic compositions or any combination thereof. Any combination of the above forms and / or compositions can be used in the present invention. Optionally, the aerogel particles can be coated with one or more materials (such as polymers or elastomers), or treated with a treatment agent such as silane. A variety of different aerogel compositions can be used, including inorganic, organic and hybrid organic-inorganic compositions. Inorganic aerogels are generally based on metal oxide compounds, including but not limited to: silicon dioxide, titanium dioxide, zirconium oxide, aluminum oxide, hafnium dioxide, yttrium oxide, or based on various carbides, nitrides or any combination of the foregoing substances. Organic aerogels can be based on compounds including, but not limited to, urethanes, resorcinol formaldehyde, polyimides, polyacrylates, chitosan, polymethyl methacrylate, members of the acrylate oligomer family, trialkoxysilyl-terminated polydimethylsiloxanes, polyoxyalkylenes, polyurethanes, polytetramethyleneimine, members of the polyether family of materials, or combinations thereof. Examples of organic-inorganic hybrid aerogels include, but are not limited to, silica-PMMA, silica-chitosan, or combinations of the aforementioned organic and inorganic compounds. In some cases, organic polymers or organic-inorganic hybrid polymers can be thermally treated to produce carbon- or inorganic-based mesoporous or microporous materials, including aerogels.

[0056] In the present invention, the silicone-based fireproofing material may exhibit a compressive strain of ≥10%, ≥15%, ≥20%, ≥25%, or ≥30% at 200 kPa.

[0057] In an embodiment of the present disclosure, the silicone-based polymer foam is obtained by curing a curable silicone-based composition comprising:

[0058] a) at least one organopolysiloxane having at least two alkenyl groups bonded to silicon per molecule;

[0059] b) at least one organosilicon crosslinker having at least two or at least three hydrogen atoms bonded to silicon (Si—H or —SiH) per molecule;

[0060] c) hollow fillers;

[0061] d) a hydrosilylation catalyst, and

[0062] e) Gas blowing agent.

[0063] In the present invention, component a) is well known in the art; and examples thereof include vinyl-terminated polydiorganosiloxane (ie, vinyl-terminated PDMS) of the following formula:

[0064]

[0065] where R 3 and R 4 Selected from the group consisting of: an alkyl group, a phenyl group, and a vinyl group each having 1 to 6 carbon atoms, wherein at least 50% of the R 4 Preferably, the viscosity of component a) at 25° C. is 8,000 to 20,000 cst, 8,000 to 16,000 cst, 8,000 to 14,000 cst, 8,000 to 12,000 cst, or 8,000 to 10,000 cst.

[0066] In some embodiments of the present disclosure, the alkenyl group included in component a) may contain 2 to 14 carbon atoms, 4 to 12 carbon atoms, or 6 to 10 carbon atoms; preferably, the alkenyl group is selected from the group consisting of vinyl, allyl, hexenyl, decenyl, and tetradecenyl, and most preferably, the alkenyl group is a vinyl group.

[0067] Particularly preferably, component a) can be incorporated into the curable silicone-based composition in an amount of 20% to 80% by weight, 30% to 60% by weight, or 40% to 50% by weight, such as 30.1% by weight, based on the total amount of the curable silicone-based composition.

[0068] In the present invention, component b) can be used to adjust the crosslinking density and can be any organosilicon with an average of at least two silicon-bonded hydrogen atoms per molecule. The remaining valence of the silicon atom is satisfied by a divalent oxygen atom or by a monovalent alkyl group having 1 to 6 carbon atoms per group (such as a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, a hexyl group, and a phenyl group). The organohydrogensiloxane can be a homopolymer, a copolymer, and a mixture thereof. Preferably, the organohydrogensiloxane is a copolymer of trimethylsiloxy and methylhydrogensiloxane, or a copolymer of trimethylsiloxy, methylhydrogensiloxane and dimethylsiloxane. In an embodiment of the present invention, the organohydrogensiloxane has an average of at least three silicon-bonded hydrogen atoms per molecule. In an embodiment of the present invention, the viscosity of component b) at 25°C is 1cst to 100cst, 1cst to 80cst, 1cst to 60cst, 1cst to 40cst, or 1cst to 20cst. In an embodiment of the present invention, component b) comprises 1 wt% to 5 wt%, 1 wt% to 4 wt%, 1 wt% to 3 wt%, 1 wt% to 2 wt%, or 1 wt% to 1.5 wt% of SiH. In an embodiment of the present invention, component b) is a hydrogenated silicone oil having a viscosity of 20 cSt at 25°C and comprising about 1.6 wt% of SiH.

[0069] Particularly preferably, component b) can be incorporated into the curable silicone-based composition in an amount of 4 to 20 wt. %, 6 to 16 wt. % or 8 to 14 wt. %, such as 12 wt. %, based on the total amount of the curable silicone-based composition.

[0070] In the present invention, component c) can be used to adjust the hardness and density of the silicone-based fireproofing material. Hollow glass beads are used to reduce the density of the foam. Hollow glass beads, in particular hollow glass microspheres, are very suitable for this application because, in addition to having excellent isotropic compressive strength, they also have the lowest density of any filler that can be used to make high compressive strength foam. The combination of high compressive strength and low density makes hollow glass microspheres a filler with many advantages according to the present invention. According to one embodiment, the hollow glass beads are hollow borosilicate glass microspheres, also known as glass bubbles or glass microbubbles. According to another embodiment, the hollow borosilicate glass microspheres have a true density in the range of 0.10 grams per cubic centimeter (g / cc) to 0.65 grams per cubic centimeter (g / cc).

[0071] According to a preferred embodiment, the hollow glass beads are selected from the group consisting of 3M® sold by 3M Company. TMGlass Bubble Float Series (A16 / 500, G18, A20 / 1000, H20 / 1000, D32 / 4500 and H50 / 10,000EPX glass bubble products) and 3M TM A series of glass bubbles (such as, but not limited to, K1, K15, S15, S22, K20, K25, S32, S35, K37, XLD3000, S38, S38HS, S38XHS, K46, K42HS, S42XHS, S60, S60HS, iM16K, iM30K glass bubble products). The glass bubbles exhibit various crush strengths ranging from 1.72 MPa (250 psi) to 186.15 MPa (27,000 psi), at which 10% by volume of the first plurality of glass bubbles collapses. Other glass bubbles sold by 3M, such as 3M TM Glass Bubble-Floating Series, 3M TM Glass Bulbs - HGS Series and 3M with Surface Treatment TM Glass bubble.

[0072] According to a preferred embodiment, the glass bubbles are selected from those exhibiting a crush strength in the range of 1.72 MPa (250 psi) to 186.15 MPa (27,000 psi), at which 10% by volume of the first plurality of glass bubbles collapses. According to a most preferred embodiment, the hollow glass beads are selected from 3M TM Glass Bubble Series, S15, K1, K25, iM16K, S32 and XLD3000.

[0073] Particularly preferably, component c) can be incorporated into the curable silicone-based composition in an amount of 1% to 15% by weight, 3% to 10% by weight, or 5% to 8% by weight, such as 4.7% by weight, based on the total amount of the curable silicone-based composition.

[0074] In the present invention, component d) the hydrosilylation catalyst can be selected from the group consisting of platinum, palladium, rhodium, nickel, iridium, ruthenium catalysts, and mixtures thereof, preferably a platinum catalyst, which can effectively promote the reaction of -SiH groups with vinyl groups and the reaction between -SiH groups and hydroxyl groups, thereby providing hydrogen for the foaming process. Particularly preferred are two-component foamable silicone compositions in which the catalyst is an organoplatinum compound. Particularly preferred are two-component foamable silicone compositions in which the catalyst is a functional organoplatinum compound selected from (η-diolefin)(α-aryl)platinum complexes, (η-diolefin)(γ-aryl)platinum complexes, (η-diolefin)(γ-alkyl)platinum complexes, and mixtures thereof. Commercially available products can be used in the present invention.

[0075] Particularly preferably, component d) may be incorporated into the curable silicone-based composition in an amount of 0.1 to 2 wt %, 0.5 to 1.5 wt % or 0.8 to 1.3 wt %, such as 1.2 wt %, based on the total amount of the curable silicone-based composition.

[0076] In the present invention, component e) may comprise a chemical blowing agent, a physical blowing agent, or a mixture of chemical and physical blowing agents. The curable silicone-based composition may be mechanically foamed or may comprise a chemical and / or physical blowing agent. To avoid the generation of explosive gases and / or volatile organic compounds, suitable physical blowing agents may be used, including those that are non-flammable and / or inert at 0°C (zero°C).

[0077] Alternatively, component e) may comprise a physical liquid blowing agent. When component e) is a physical liquid blowing agent, the physical liquid blowing agent is tailored to undergo a phase change at the application temperature. When component e) is a physical blowing agent, the phase change at the application temperature is the primary source of gas that causes foam formation by replacing all or most of the hydrogen produced when using a chemical blowing agent.

[0078] When component e) is a physical blowing agent, the physical blowing agent selected is selected based on its boiling point so that it undergoes a phase transition from liquid to gas during exposure to atmospheric pressure and the temperature of the curing process (e.g., a temperature of less than or equal to 10° C., alternatively less than or equal to 20° C., alternatively less than or equal to 30° C., alternatively less than or equal to 40° C., alternatively less than or equal to 50° C., alternatively less than or equal to 60° C., alternatively less than or equal to 70° C., alternatively less than or equal to 80° C., alternatively less than or equal to 90° C., alternatively less than or equal to 100° C.). In the case of a room temperature vulcanizing system, the physical blowing agent selected may have a boiling point between 10° C. and 30° C., i.e., such that the physical blowing agent undergoes a phase transition from liquid to gas during exposure to atmospheric pressure within this temperature range.

[0079] When component e) is a physical blowing agent, the amount of physical blowing agent utilized can vary depending on the desired results. For example, the amount of physical blowing agent can be varied to adjust the final foam density and the foam rise profile of the resulting insulation.

[0080] Useful physical blowing agents include hydrocarbons (such as pentane, hexane, halogenated hydrocarbons, more specifically chlorinated and / or fluorinated hydrocarbons, for example, methylene chloride, chloroform, trichloroethane, chlorofluorocarbons, hydrochlorofluorocarbons (HCFCs)), ethers, ketones, and esters (for example, methyl formate, ethyl formate, methyl acetate, or ethyl acetate), in liquid form or as a gas, air, nitrogen, or carbon dioxide. In certain embodiments, the physical blowing agent comprises a compound selected from the group consisting of propane, butane, isobutane, isobutylene, isopentane, dimethyl ether, or mixtures thereof. In many embodiments, the blowing agent comprises an inert compound.

[0081] In various embodiments, the physical blowing agent comprises a hydrofluorocarbon (HFC). "Hydrofluorocarbon" and "HFC" are interchangeable terms and refer to organic compounds containing hydrogen, carbon, and fluorine. The compound is substantially free of halogens other than fluorine.

[0082] Examples of suitable HFCs include aliphatic compounds such as 1,1,1,3,3-pentafluoropropane, 1,1,1,3,3-pentafluorobutane, 1-fluorobutane, nonafluorocyclopentane, perfluoro-2-methylbutane, 1-fluorohexane, perfluoro-2,3-dimethylbutane, perfluoro-1,2-dimethylcyclobutane, perfluorohexane, perfluoroisohexane, perfluorocyclohexane, perfluoroheptane, perfluoroethylcyclohexane, perfluoro-1,3-dimethylcyclohexane, and perfluorooctane; and aromatic compounds such as fluorobenzene, 1,2-difluorobenzene; 1,4-difluorobenzene, 1,3-difluorobenzene; 1,3,5-trifluorobenzene; 1,2,4,5-tetrafluorobenzene, 1,2,3,5-tetrafluorobenzene, 1,2,3,4-tetrafluorobenzene, pentafluorobenzene, hexafluorobenzene, and 1-fluoro-3-(trifluoromethyl)benzene. In certain embodiments, compounds such as 1,1,1,3,3-pentafluoropropane and 1,1,1,3,3-pentafluorobutane may be preferred due to their increased availability and ease of use, wherein 1,1,1,3,3-pentafluorobutane has a higher boiling point than 1,1,1,3,3-pentafluoropropane, which may be useful in certain applications. For example, HFCs with boiling points above 30° C. (such as 1,1,1,3,3-pentafluorobutane) may be desirable because they do not require liquefaction during foam processing. In specific embodiments, when component e) is a physical blowing agent, component e) comprises 1,1,1,3,3-pentafluoropropane.

[0083] When component e) comprises a chemical foaming agent, it comprises one or more hydroxy-containing foaming agents, which will react with the crosslinking agent (b) in the presence of the component (d) catalyst. When component e) is a chemical foaming agent comprising one or more hydroxy-containing foaming agents, each hydroxy-containing foaming agent has at least one hydroxyl (OH) group, alternatively at least two OH groups, and alternatively three or more OH groups. The OH group can react with the Si-H group of component (b) to generate hydrogen, which is relied upon to generate foam. Each hydroxy-containing foaming agent can be a suitable alcohol. These alcohols can be selected from aliphatic organic alcohols with 1 to 12 carbon atoms, such as low molecular weight alcohols, including but not limited to methanol, ethanol, propanol, isopropanol, etc., or alternatively benzyl alcohol.

[0084] In one embodiment, the hydroxyl-containing blowing agent can be a diol. Examples of suitable diols include, but are not limited to, methylene glycol, ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, butanediol, bisphenol A, 1,4-butanediol, 1,3-propylene glycol, 1,5-pentanediol, 1,7-heptanediol, 1,2-hexanediol, triethylene glycol, tripropylene glycol, neopentyl glycol, and combinations thereof. Alternatively, the hydroxyl-containing blowing agent can be a triol.

[0085] In various embodiments, component e) (when acting as a hydroxyl-containing blowing agent) is selected from the group of low-boiling alcohols. Most (but not all) of these alcohols have a boiling point below about 120°C. The alcohol may or may not be anhydrous, but anhydrous alcohols (containing less than 1% by weight of water, based on the weight of the alcohol) are generally preferred. Other suitable blowing agents are described in US Pat. No. 4,550,125, US Pat. No. 6,476,080, and US Pat. No. 2014,002,4731, which are incorporated herein by reference.

[0086] Component e) (when acting as a hydroxyl-containing blowing agent) is present in an amount to provide an OH content of about 10 parts per million (ppm) to 50,000 ppm, alternatively about 100 ppm to 20,000 ppm, alternatively about 500 ppm to 10,000 ppm, alternatively about 500 to about 7500 ppm.

[0087] In other embodiments, when component e) is a chemical blowing agent, the chemical blowing agent can be selected from the group of Si-OH polymers. In certain embodiments, when used as a chemical blowing agent, component e) is selected from the group consisting of organosilanes and organosiloxanes having at least one silanol (Si-OH) group. The structures of such compounds can be similar to those of the polymers described above for component (a).

[0088] Examples of suitable OH-functional compounds include dialkylsiloxanes, such as OH-terminated dimethylsiloxanes. Such siloxanes may have a relatively low viscosity, such as from about 15 mPa.s to about 20,000 mPa.s, from about 15 mPa.s to about 10,000 mPa.s, from about 15 mPa.s to about 5,000 mPa.s, from about 15 mPa.s to about 1,000 mPa.s, or from about 15 mPa.s to about 100 mPa.s, measured at 25°C. The viscosity may be measured at 25°C using a Brookfield TM - a rotational viscometer (designed for viscosities in the range of -200 mPa.s to 400,000 mPa.s) or for viscosities less than 200 mPa.s use a Brookfield™ rotational viscometer with an LV-1 spindle (designed for viscosities in the range of 15 mPa.s to 20,000 mPa.s) and adjust the speed (i.e. shear rate, e.g. from 0.005 s -1 Adjust to 1s -1 (0.3 rpm to 60 rpm), in this case, 1 s is preferred -1 ) to measure.

[0089] In an alternative embodiment of the present invention, component e) may have at least one hydroxyl group, including one, two or more hydroxyl groups, or a mixture of compounds having at least one hydroxyl group. The hydroxyl group of component e) may react with the silicon-hydrogen group (SiH) of the organosilicon having at least two -SiH groups (hydrosilyl groups) to produce hydrogen gas and thereby generate cells in the foam. In some embodiments of the present disclosure, component e) is selected from silanols, alcohols, water, and mixtures thereof.

[0090] In one embodiment of the present disclosure, the alcohol may have 1 to 12 carbon atoms. Examples of alcohols include methanol, ethanol, propanol, isopropanol, butanol, and the like. Alcohols can react with hydrogen atoms on silicon in the presence of a platinum catalyst to produce additional hydrogen. Preferably, the alcohol is a monohydric alcohol. When a monohydric alcohol is used, no corresponding crosslinks are formed, and thus the resulting foam tends to have fewer crosslinks than in the absence of the alcohol. Foams formed using an alcohol tend to have a lower density than in the absence of the alcohol.

[0091] Particularly preferably, component e) may be incorporated into the curable silicone-based composition in an amount of 0.1 to 5 wt %, 0.5 to 3 wt %, or 1.0 to 2 wt %, such as 1.9 wt %, based on the total amount of the curable silicone-based composition.

[0092] In some embodiments of the present disclosure, the curable silicone-based composition further comprises:

[0093] f) at least one additive selected from the group consisting of inhibitors that slow down the curing rate, reactive diluents that react by a hydrosilylation reaction, pigments, dyes, clays, surfactants, hydrogenated castor oil, wollastonite, aluminum trihydrate, magnesium hydroxide, halloysite, magnesite hydromagnesite, expandable graphite, zinc borate, mica, and fumed silica.

[0094] In some embodiments of the present disclosure, the curable silicone-based composition further comprises:

[0095] g) at least one member selected from the group consisting of flame retardant additives, curing catalysts, rheology modifiers, wetting additives, surface treatment agents, colorants, fillers other than hollow fillers, hydrosilylation catalyst inhibitors, foam boosters, antioxidant additives, biocides, reinforcing resins, ultraviolet (UV) stabilizer additives, and adhesion promoter additives.

[0096] In the present invention, the flame retardancy of the silicone-based fireproofing material can be further improved by adding a flame retardant additive. Typically, there is 0% to 40% by weight, 10% to 30% by weight, or 15% to 25% by weight of the flame retardant additive, depending on the flame retardancy requirements of the silicone-based fireproofing material. The flame retardant additive may include non-combustible fibers and sulfur-free carbon black. Non-combustible fibers are believed to help retain the char formed when the foam is subjected to flames to protect the foam under the carbonized surface. The non-combustible fibers can be selected from fibers such as carbon fibers, ceramic fibers, and aramid fibers, with ceramic fibers being preferred. The fibers should be fine fibers with an average diameter of less than 5 microns and a length of less than 100 mm so that the fibers can be evenly and easily distributed throughout the mixture. Preferably, there is 1% to 5% by weight of non-combustible fibers and 1% to 5% by weight of sulfur-free carbon black. The added carbon black can be any conventional sulfur-free carbon black used as an additive in silicone elastomers cured with platinum catalysts. The carbon black is sulfur-free because sulfur may interfere with curing.

[0097] In some embodiments of the present disclosure, the flame retardant additive includes a halogenated flame retardant additive and / or a non-halogenated flame retardant additive, wherein examples of halogenated flame retardant additives include brominated flame retardant additives, such as brominated polymers or oligomers, brominated styrene-butadiene-styrene copolymers, and preferably a combination of brominated flame retardant additives and antimony trioxide for forming a Br-Sb synergistic system; and examples of non-halogenated flame retardant additives may include ammonium polyphosphate, melamine polyphosphate, aluminum hydroxide, magnesium hydroxide, expandable graphite. In the present invention, the flame retardant additive may be dispersed or distributed throughout the silicone-based polymer binder (i.e., polymer matrix) in a loading amount ranging from 0% to 60% by mass of the dry material. A flame retardant additive with a loading amount> 60% by mass may result in insufficient thermal insulation performance required in battery fire protection applications.

[0098] In the present invention, the (hydrosilylation catalyst) inhibitor can slow down the reaction rate so that mixing can be completed before the mixture begins to form foam. Examples of hydrosilylation catalyst inhibitors include methylvinylcyclosiloxane, tetravinyltetramethylcyclotetrasiloxane (vinyl D4), ethynylcyclohexanol (ECH), and mixtures thereof. Particularly preferably, the hydrosilylation catalyst inhibitor can be incorporated into the curable silicone-based composition in an amount of 0% to 2% by weight, 0.5% to 1.5% by weight, or 0.8% to 1.2% by weight, such as 0.7% by weight, based on the total amount of the curable silicone-based composition, depending on the desired cure speed.

[0099] Fillers other than the hollow fillers include, but are not limited to, (fumed) silica, diatomaceous earth, crushed quartz, zinc oxide, calcite, aluminum hydroxide, CaCO3 and hydromagnesite, fibrous potassium titanate or other well-known fillers for silicone-based fireproofing materials. The maximum amount of fillers other than the hollow fillers used will depend on the viscosity of the curable silicone-based composition.

[0100] In the present invention, a foam booster can be used to adjust the morphology of the foam formed, which produces a modified foam with smaller, more uniform cells (preferably predominantly closed) and allows the production of foams with different combinations of properties, such as density, compressibility, and resilience. The foam booster comprises a resinous, benzene-soluble organosiloxane copolymer, wherein the repeating units include, but are not limited to, SiO 4 / 2 Unit, (CH3)3SiO 1 / 2 units and fluorine-containing units containing at least one perfluorinated carbon atom. Each of the fluorine-containing units further comprises one or two silicon atoms, which are linked to the fluorine-containing carbon atom via a sequence of at least two methylene (-CH2-) units or via an oxygen atom which is in turn bonded to the sequence. Examples of foam boosters include fluorinated silicone resins.

[0101] Particularly preferably, the foam booster may be incorporated into the curable silicone-based composition in an amount of 0 to 10 wt %, 3 to 8 wt %, or 5 to 6 wt %, such as 7.5 wt %, based on the total amount of the curable silicone-based composition, depending on the desired curing speed.

[0102] The reinforcing resin can improve mechanical requirements, and examples thereof include a blend of PDMS and a resin, wherein the amount of the resin is 35 wt%, the vinyl group is 0.84 wt%, and the viscosity at 25° C. is 5000 cst, etc. Particularly preferably, the reinforcing resin can be incorporated into the curable silicone-based composition in an amount of 0 wt% to 50 wt%, 10 wt% to 40 wt%, or 20 wt% to 30 wt%, such as 30.4 wt%, based on the total amount of the curable silicone-based composition.

[0103] Rheology modifiers are used to adjust the viscosity of the wet slurry, for example, in amounts ranging from 0 to 2 mass % in the wet slurry. Curing catalysts include dioctyltin dilaurate or others, depending on the curing chemistry. Wetting additives are used to wet the surface of hydrophobic fillers. Colorants can impart the desired color to silicone-based fireproofing materials.

[0104] In the present invention, the method for producing the silicone-based fireproof material comprises the following steps:

[0105] Step (I): providing a part A comprising a) at least one organopolysiloxane having at least two alkenyl groups bonded to silicon per molecule and e) a gaseous blowing agent;

[0106] Step (II): providing a part B comprising b) at least one organosilicon crosslinker having at least two hydrogen atoms bonded to silicon per molecule and optionally e) a gaseous blowing agent as a physical blowing agent;

[0107] Step (III): a step of mixing Part A with Part B to form a curable silicone-based composition;

[0108] Step (IV): a step of applying the curable silicone-based composition as a wet slurry layer onto a substrate optionally having a release layer, and

[0109] Step (V): a step of forming a silicone-based fireproof material by curing and foaming the applied curable silicone-based composition.

[0110] In some embodiments of the present disclosure, components (a) to (g) can be combined in any combination to make two parts for storage, as long as the chemical blowing agent as a gas blowing agent and the organopolysiloxane containing alkenyl groups are not present together with the organosilicon crosslinking agent containing Si-H. For optimal shelf life, it is not desirable to have a hydrosilylation catalyst and an organopolysiloxane in the same package. In some embodiments of the present disclosure, components c), d), f) and g) can be added independently to part A, part B or both. In the method for producing the silicone-based fireproof material of the present invention, when a physical blowing agent is used as a gas blowing agent, it can be incorporated into part A, part B or both.

[0111] In an embodiment of the present invention, the method for producing the silicone-based fireproof material may further include: before mixing part A with part B, adding flame retardant additives, curing catalysts, rheology modifiers, wetting additives, surface treatment agents, colorants, fillers other than hollow fillers, antioxidant additives, biocides, ultraviolet (UV) stabilizer additives and adhesion promoter additives to part A, part B or both.

[0112] In an embodiment of the present invention, the method for producing the silicone-based fireproof material may further include: after mixing part A with part B, adding a flame retardant additive, a curing catalyst, a rheology modifier, a wetting additive, a surface treatment agent, a colorant, a filler other than a hollow filler, an antioxidant additive, a biocide, an ultraviolet (UV) stabilizer additive and an adhesion promoter additive to the curable silicone-based composition.

[0113] In an embodiment of the present invention, the method for producing the silicone-based fire-proof material may further include: in step (IV), the wet slurry layer of the curable silicone-based composition has a thickness of 0.2 mm to 10.0 mm, 0.2 mm to 6.0 mm, 0.2 mm to 2.0 mm, 0.2 mm to 1.0 mm, 1.0 mm to 10.0 mm, 1.0 mm to 6.0 mm, 1.0 mm to 2.0 mm, 2.0 mm to 10.0 mm, 2.0 mm to 6.0 mm or 6.0 mm to 10.0 mm.

[0114] In an embodiment of the present invention, the method for producing the silicone-based fireproof material may further comprise: before or simultaneously with step (IV), a step of controlling the viscosity and / or fluidity of the curable silicone-based composition by a rheology modifier.

[0115] In an embodiment of the present invention, the method of producing the silicone-based fire-proofing material may further include removing the silicone-based fire-proofing material from a substrate (such as release paper).

[0116] In the present invention, the silicone-based fireproof material can be used in a secondary battery pack including at least one battery module housing, wherein the housing includes a plurality of battery cells electrically connected to each other. The battery cells are preferably prismatic or pouch-shaped, and the battery cells are preferably protected by the silicone-based fireproof material.

[0117] In an embodiment of the present invention, a battery pack structure is described, in which the silicone-based fireproofing material is arranged entirely or partially in the space between at least two adjacent individual battery cells. When preparing the battery pack structure, the silicone-based fireproofing material can be cured before being arranged in the space between at least two adjacent individual battery cells. In this production method of the battery pack structure, the "cured" silicone-based fireproofing material can be arranged (including inserted) entirely or partially in the space between at least two adjacent individual battery cells to prevent heat transfer from the hot surface of the "fired" cell due to the thermal runaway of the "fired" cell propagating to the adjacent good cells.

[0118] In addition, the silicone-based fireproof material can be arranged in the space between at least two adjacent individual battery cells by the curing reaction of the curable silicone-based composition in the space. In this embodiment of the present invention, a curable silicone-based composition is used to prepare the battery pack structure, and the curable silicone-based composition can be cured into the silicone-based fireproof material. More specifically, this production method of the battery pack structure includes the following steps: step (BI): a step of completely or partially filling the space between at least two adjacent individual battery cells with a curable silicone-based composition according to any one of claims 13 to 14 as a wet slurry layer; and step (B-II): a step of forming a silicone-based fireproof material in the space between at least two adjacent individual battery cells by curing and foaming the curable silicone-based composition.

[0119] Any of the production methods may be employed to arrange the silicone-based fireproof material into the space between at least two adjacent individual battery cells, taking into account its step requirements in the battery assembly process or the required fireproof performance of the battery pack structure.

[0120] The silicone-based fireproof material partially or completely fills the open space of the battery module housing and / or partially or completely covers the battery cells, and / or partially or completely covers the module housing, and optionally covers the cover of the battery module housing. The silicone-based fireproof material is obtained by dispersing hollow fillers into silicone-based polymer foam, applying it to a certain wet thickness, and forming the final material with hollow fillers and bubbles. The silicone-based fireproof material can also be assembled between the water-cooling plate and the metal plate of the battery housing to prevent heat diffusion between the water-cooling plate and the metal plate of the battery housing. The silicone-based fireproof material of the present invention can be prefabricated and then assembled into the battery housing. The silicone-based fireproof material of the present invention can also be manufactured by pouring the wet slurry obtained by dispersing the hollow filler into the liquid silicone composition into the cavity between the cells in the battery housing, and forming a final solidified and foamed material.

[0121] Example

[0122] Certain embodiments of the present invention will now be described in the following examples, in which all parts and percentages are by weight unless otherwise indicated.

[0123] The following Table 1 lists the information of the raw materials used in the examples:

[0124] Table 1. Raw materials used in the examples

[0125]

[0126] Inventive Example 1-2 (IE 1-2) and Comparative Example 1-2 (CE 1-2)

[0127] In Inventive Examples 1-2 of the present disclosure, silicone-based fireproof materials were produced using those raw materials and their amounts described in Table 2. Comparative Examples 1-2 are provided herein as controls.

[0128] Table 2: Formulations used in Examples and Comparative Examples

[0129] Part A :

[0130] Ingredient Type name CE1 CE2 IE1 IE2 Organopolysiloxane P-1 55 31.9 31.0 30.4 Filler 1 F-1 24.5 23.8 23.4 Filler 2 F-2 2.9 4.7 Filler 3 F-3 10 resin R-1 35 31.9 31.0 30.4 catalyst CAT-1 0.5 1.3 1.2 1.2 inhibitors INH-1 0.7 0.7 0.7 Foam booster PF-1 7.8 7.6 7.5 foaming agent B-1 2.0 1.9 1.9

[0131] Part B :

[0132] Ingredient Type name CE1 CE2 IE1 IE2 Organopolysiloxane P-1 55 31.6 30.7 30.1 filler F-1 24.3 23.6 23.1 filler F-2 2.8 4.6 filler F-3 10 resin R-1 30 31.6 30.7 30.1 crosslinking agent CX-1 5 12.6 12.3 12.0

[0133] For IE1-2 and CE1-2, they involve six steps:

[0134] Step 1: Prepare Part A as a wet slurry;

[0135] Step 2: Prepare Part B into a wet slurry;

[0136] Step 3: Mixing Part A with Part B to form a curable silicone-based composition as a mixed wet slurry;

[0137] Step 4: Apply the mixed wet slurry on the substrate with the release layer;

[0138] Step 5: curing and foaming the mixed wet slurry to form a silicone-based fireproofing material; and

[0139] Step 6: Test the thermal insulation performance of silicone-based fireproofing materials at high temperatures.

[0140] A detailed description of steps 1-6 is provided below:

[0141] Step 1: Prepare Part A

[0142] P-1, R-1, CAT-1, INH-1 (if necessary), B-1, and PF-1 (if necessary) were added to a 1-liter plastic cup and mixed at 300 rpm using a Cowles paddle to form a uniform slurry. F-1 was then slowly added while stirring at 300 rpm to ensure dispersion of F-1 and to prevent agglomeration. After complete dispersion and viscosity increase, F-2 and / or F-3 (if necessary) were gradually added while stirring at 300 rpm to prepare a uniform slurry.

[0143] Step 2: Prepare Part B

[0144] P-1, R-1, and CX-1 were added to a 1-liter plastic cup and mixed at 300 rpm with a Cowles blade to form a uniform slurry. F-1 was then slowly added while stirring at 300 rpm to ensure dispersion of F-1 and to prevent agglomeration. After it was fully dispersed and the viscosity increased, F-2 and / or F-3 (if necessary) were gradually added while stirring at 300 rpm to prepare a uniform slurry.

[0145] Step 3: Mix Part A and Part B

[0146] Mix Part A with Part B under stirring at 300 rpm to prepare a homogeneous slurry.

[0147] Step 4: Apply the wet slurry to the substrate

[0148] The slurry obtained in step 3 was coated on a PTFE sheet with a doctor blade so as to form a wet sheet having a thickness of 1 mm.

[0149] Step 5: Allow the mixed wet slurry to cure and foam

[0150] The wet sheet obtained in step 4 was dried in an oven at 90° C. for 1 hour to obtain a dried sheet.

[0151] Step 6: Test the insulation performance at high temperature .

[0152] The dried sheet was cut into 8 cm x 8 cm squares, placed on a heating table stabilized at 600°C, and mounted to an Al plate with an outer diameter (OD) of 0.5 mm partially embedded in a 0.4 mm groove with two K-type thermocouples, which was in close contact with the back surface of the specimen to record the back temperature. All surfaces of the Al plate were well covered with insulating asbestos sheets to control heat diffusion. A steel load was further mounted on the Al plate to generate a pressure of 0.03 MPa on the specimen. The description of this setup is given in Figure 1 . All installations were completed within 10 seconds of the specimen being attached to the heating stage. The heating stage temperature of 600°C was calibrated by mounting a square 8cm×8cm aerogel sheet / pad with a thickness of 4±0.2mm onto an Al plate, with a thermocouple on the center of the sheet in direct contact with the heating stage surface. The calibration lasted for at least 20min for a stable 600°C heating stage surface before starting the thermal insulation performance test. In the test, the back temperature was recorded from the time the specimen was attached to the heating stage. The test lasted 20min. The original thickness of the sheet specimen was measured at the four corners, and the average thickness was calculated. During the test, a feeler gauge was inserted between the heating stage and the Al plate to measure the thickness just before the end of the test. The post-temperature change with the test duration was recorded.

[0153] Table 3: Thermal insulation performance test results

[0154]

[0155]

[0156] Compared to CE1, which does not contain a blowing agent, both IE1 and IE2 exhibit lower density and excellent thermal insulation properties. Their viscosity is approximately 16,000 mPa*s, making them well-suited for roll-to-roll casting and potting processes. Furthermore, their thermal insulation and flame retardancy are significantly improved. Due to the presence of bubbles with a certain volume fraction, their compressive strain at 200 kPa meets the requirements for battery packs with prismatic or pouch-shaped cells.

[0157] CE1 contains approximately 10% hollow glass beads, which significantly increase the viscosity of the curable silicone-based composition. CE1 has a density of 0.8 g / cc, which is higher than IE1 and IE2 of the present invention. Thermal insulation testing showed that the back temperature of CE1 reached 231.4°C, close to the critical temperature (250°C) that can cause thermal runaway of adjacent battery cells. CE1's compressive strain at 200 kPa was only 7.97%, which is lower than the minimum requirement required to absorb thickness variations of the prismatic cells during module or battery pack assembly.

[0158] CE2 is an H2-expanded silicone foam without hollow glass beads. It has low density and hardness. However, it has poor insulation performance because it can be easily compressed during insulation testing.

[0159] IE1 and IE2 contain less than 5% hollow glass beads by volume and have a much lower viscosity. This is because the 1-propanol blowing agent reacts with the Si-H crosslinker and releases H2 gas, which creates a large amount of pores / voids during the curing process. Despite their low density, IE1 and IE2 have a higher hardness, which enables IE1 and IE2 to have low thermal conductivity and suitable buffering properties, making them better suited for thermal barrier applications between individual cells in battery packs.

[0160] Testing and Evaluation

[0161] Viscosity

[0162] The viscosity of the curable silicone-based composition was measured according to ASTM D1084.

[0163] density

[0164] The density of silicone-based fire protection materials is measured according to ASTM D792.

[0165] Hardness (Shore A)

[0166] The hardness of silicone-based fire protection materials is measured according to ASTM D 2240.

[0167] Flame retardant properties

[0168] Measuring the flame retardant properties of silicone-based fire protection materials according to UL 94.

[0169] Insulation (back temperature ℃)

[0170] Figure 1 The experimental setup for the thermal insulation performance test is shown. 2The sample was placed on a heater at 600°C for 20 minutes. Two thermocouples were placed on the back of the sample to monitor the temperature. An aluminum block was placed on top of the sample to simulate adjacent battery cells in a battery module. On top of the aluminum block, several iron blocks were added to simulate the pressure (0.03 MPa) during the thermal runaway process.

[0171] Electrical insulation

[0172] The dielectric strength of silicone-based fire protection materials is measured according to ASTM D 149, and their volume resistivity is measured according to ASTM D257.

[0173] Volume fraction of hollow fillers

[0174] The volume fraction of the hollow filler was calculated by the following equation.

[0175] R 体积 =R 重量 ×ρ 泡沫 / ρ 中空填料

[0176] R 体积 is the volume fraction of the hollow filler, R 重量 is the weight fraction of hollow filler, ρ 泡沫 is the density of the foam, ρ 中空填料 is the density of the hollow filler.

[0177] Bubble volume fraction

[0178] The volume fraction of bubbles is calculated by the following equation.

[0179] R 气体 =1–R 体积 –(1–R 重量 )×ρ 泡沫 / ρ 浆料

[0180] R 气体 is the volume fraction of bubbles, R 体积 is the volume fraction of the hollow filler, R 重量 is the weight fraction of hollow filler, ρ 泡沫 is the density of the foam, ρ 浆料 is the density of the uncured formulation without hollow fillers, which is 1.1 g / cc for the formulation of the example.

[0181] compressive strain

[0182] The compression strain was measured by Instron 5566. The sample size was 36 mm*36 mm*3.4 mm; and the compression speed was controlled at 1 mm / min.

Claims

1. A fireproof material based on silicone having a foam structure, wherein the foam structure has a d 50 The hollow filler is incorporated into a silicone-based polymer foam containing air bubbles, wherein the silicone-based fireproofing material has a density of 0.1 g / cc to 0.8 g / cc and a Shore A hardness of 1-40, and the silicone-based polymer foam has a bubble size d of 10 microns to 1000 microns. 50 . 2 . The organic silicon-based fireproof material according to claim 1 , wherein the volume fraction of the hollow filler is 1%-60% based on the total volume of the organic silicon-based fireproof material. 3 . The organic silicon-based fireproof material according to claim 1 , wherein the volume fraction of the bubbles is 5% to 90% based on the total volume of the organic silicon-based fireproof material.

4. The silicone-based fireproof material according to claim 1, wherein the hollow filler is selected from hollow glass beads, aerogel particles, perlite beads, hollow ceramic beads, floating beads and polymer hollow beads.

5. The silicone-based fireproof material according to claim 1, wherein the silicone-based polymer foam is obtained by curing a curable silicone-based composition, the curable silicone-based composition comprising: a) at least one organopolysiloxane having at least two alkenyl groups bonded to silicon per molecule, b) at least one organosilicon crosslinker having at least two hydrogen atoms bonded to silicon per molecule, c) hollow fillers, d) a hydrosilylation catalyst, and e) Gas blowing agent.

6. The silicone-based fireproofing material according to claim 5, wherein the curable silicone-based composition further comprises: f) at least one additive selected from the group consisting of inhibitors that slow down the curing rate, reactive diluents that react by a hydrosilylation reaction, pigments, dyes, clays, surfactants, hydrogenated castor oil, wollastonite, aluminum trihydrate, magnesium hydroxide, halloysite, magnesite hydromagnesite, expandable graphite, zinc borate, mica, and fumed silica.

7. The silicone-based fireproofing material according to claim 5, wherein the curable silicone-based composition further comprises: g) at least one selected from the group consisting of flame retardant additives, curing catalysts, rheology modifiers, wetting additives, surface treatment agents, colorants, fillers other than the hollow filler, antioxidant additives, biocides, ultraviolet (UV) stabilizer additives, and adhesion promoter additives. 8 . The silicone-based fireproof material according to claim 1 , which is applied to a battery pack.

9. The silicone-based fireproofing material according to any one of claims 1 to 7, wherein the silicone-based fireproofing material exhibits a compressive strain of ≥10% at 200 kPa.

10. A battery pack structure, wherein the silicone-based fireproof material according to any one of claims 1 to 9 is entirely or partially arranged in a space between at least two adjacent individual battery cells. The battery pack structure according to claim 10 , wherein the battery cell is selected from a prismatic cell and a pouch cell. 12 . The battery pack structure according to claim 10 , wherein the silicone-based fireproofing material is silicone-based and is cured before being arranged in the space between at least two adjacent individual battery cells.

13. The battery pack structure according to claim 10, wherein the silicone-based fireproofing material is a silicone-based product cured by a curing reaction of a curable silicone-based composition in the space between at least two adjacent individual battery cells, wherein the curable silicone-based composition comprises: a) at least one organopolysiloxane having at least two alkenyl groups bonded to silicon per molecule, b) at least one organosilicon crosslinker having at least two hydrogen atoms bonded to silicon per molecule, c) hollow fillers, d) a hydrosilylation catalyst, and e) Gas blowing agent.

14. A curable silicone-based composition, which forms the silicone-based fire-proof material according to any one of claims 1 to 9 through a curing reaction, the curable silicone-based composition comprising: a) at least one organopolysiloxane having at least two alkenyl groups bonded to silicon per molecule, b) at least one organosilicon crosslinker having at least two hydrogen atoms bonded to silicon per molecule, c) hollow fillers, d) a hydrosilylation catalyst, and e) Gas blowing agent.

15. The curable silicone-based composition of claim 14, wherein the alkenyl groups each contain 2 to 14 carbon atoms.

16. A method for producing a silicone-based fireproof material according to any one of claims 1 to 9, the method comprising the steps of: Step (I): providing a part A comprising a) at least one organopolysiloxane having at least two alkenyl groups bonded to silicon per molecule and e) a gaseous blowing agent; Step (II): providing a part B comprising b) at least one organosilicon crosslinker having at least two hydrogen atoms bonded to silicon per molecule and optionally e) a gaseous blowing agent as a physical blowing agent; Step (III): a step of mixing Part A with Part B to form a curable silicone-based composition according to any one of claims 14 to 15; Step (IV): a step of applying the curable silicone-based composition as a wet slurry layer onto a substrate optionally having a release layer, and Step (V): a step of forming the silicone-based fire-proof material by curing and foaming the applied curable silicone-based composition.

17. The method for producing a silicone-based fireproof material according to claim 16, wherein in step (IV), the wet slurry layer of the curable silicone-based composition has a thickness of 0.2 mm to 10.0 mm.

18. The method for producing a silicone-based fireproof material according to claim 16, further comprising the step of controlling the viscosity and / or fluidity of the curable silicone-based composition by adding a rheology modifier before or simultaneously with step (IV).

19. A method of producing the battery pack structure according to claim 10, comprising the step of arranging the silicone-based fireproofing material according to any one of claims 1 to 8 entirely or partially into a space between at least two adjacent individual battery cells.

20. A method for producing the battery structure according to claim 10, the method comprising the steps of: Step (BI): a step of completely or partially filling the space between at least two adjacent individual battery cells with the curable silicone-based composition according to any one of claims 14 to 15 as a wet slurry layer, and Step (B-II): a step of forming a silicone-based fire-proofing material in the space between at least two adjacent individual battery cells by curing and foaming the curable silicone-based composition.

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